Lecture Notes on 21 Sep 2012

# Write a boolean expression that evaluates to True if y is a leap year
(y % 400 == 0) or ((y % 100 != 0) and (y % 4 == 0))

# Loops
while (cond):
  # do this

while (True):
  # do this

# Keep prompting the user till he enters a positive number
num = eval (input ("Enter a positive number: "))
while ( num < 0 ):
  num = eval (input ("Enter a positive number: "))


# Keep prompting the user to enter a valid month
month = eval (input ("Enter the month: "))
while ((month < 1) or (month > 12)):
  month = eval (input ("Enter the month: "))